Envelope following has been used in lower bandwidth systems to modulate the supply power of radio frequency (RF) power amplifiers to save power. These systems may be limited, however, by the requirement that the power switching frequency substantially exceed the bandwidth of the RF envelope. In the case of newer communication standards such as long term evolution (LTE) and Wideband Code Division Multiple Access (WCDMA), maintaining the switching frequency above the RF bandwidth may not be practical. Switching frequency is typically limited to about 6 megahertz (MHz), whereas the RF envelope bandwidth for LTE, for example, is about 20-40 MHz. To track an LTE bandwidth envelope using existing methods and apparatus can require a switching frequency greater than 60 MHz. For example, generation of an envelope in the digital domain and conversion to analog with a digital-to-analog converter (DAC) can require increased silicon die area and power comsumption due to the higher data rate and bandwidth associated with the envelope. This can limit design flexibility and options for newer RF communication standards such as third generation (3G), fourth generation (4G), and other future RF applications because these higher bandwidth, higher frequency DAC implementations can exceed power budgets.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.